Method of making valve bags



y 7, 1957 M. D. BURRELL 2,791,160

METHOD OF MAKING VALVE BAGS Filed Feb. 15, 1954 2 Sheets-Sheet 1 Fe 3 F" 1 I INVENTOR MgoxvfiBuxma;

May 7, 1957 M. D. BURRELL METHOD OF MAKING VALVE BAGS 2 Sheets-Sheet 2 Filed Feb. 15, 1954 INVE NTOR Mwg/ MBMQQELL M 44,

7 ATTORNEY United States Patent METHOD OF MAKING VALVE'BAGS Marion D. Burrell, San Francisco, Calif., assignor to Crown Zellerbach Corporation, San Francisco, Calif., a corporation of Nevada Application February 15, 1954, Serial No. 410,258

2 Claims. (Cl. 93-35) This invention relates to valve bags of a well-known type in which a tubular multiply bag that is sewed or otherwise closed at both ends, has an intumed corner with a valve flap included in the corner and projecting into the bag to form a seal.

. In this type of bag the inturne'd corner provides a so-called valve opening through which a tube may be inserted for filling the bag. When the tube is withdrawn, the valve flap forms a seal to prevent leakage of the bag contents.

-It has been customary to insert the valve flap by hand in some cases with an adhesive to hold it in place and in some instances the flap is inserted automatically during the formation of the bag by complex machinery.

It is the object of the present invention to provide a valve bag and method of making the same wherein the valve flap is included in the original formation of the tube from which the bags are made and is by a simple adjustment drawn to an operative position before the final closing or sea-ling of the bag ends.

A further object of the invention is to provide a flap for a valve bag that is held securely in its proper position without the necessity of adhesives or other securing means.

'Further objects and advantages of the invention are made apparent in the following specification wherein the bag and the method of making it are described in detail by reference to the accompanying drawings.

In the drawings: 7

Fig. 1 is a schematic view illustrating the arrangement of a. plurality of supply rolls which feed a tuber and illustrating the relationship thereto of an auxiliary supply roll for feeding a valve strip to the .same tuber,

Fig. 2 is a schematic view showing, as though viewed in plan, the relationship of the several paper webs and the valve web as they move toward the tuber,

Fig. 3 is a View in plan of a completed bag after it has been cut from the tube with the position of the valve flap member indicated,

Fig. 4 is an enlarged schematic end view of the bag shown in Fig. 3 with the bag spread to a partially open position and showing the relationship of the valve member to the several tubes or plies which form the bag.

Fig. 5 is a view like Fig. 3 showing the valve member partially withdrawn from the bag so that it will as sume an operative position when the bag is completed, and

Fig. 6 is an enlarged fragmentary view of one corner of the bag, referred to as the valve corner, with the front wall of the bag broken away to disclose the valve construction therein.

It is customary in the formation of bags of the kind referred to to feed a plurality of sheets or plies to a machine known as a tuber and in which machine the several plies are folded into tubular form with gussetcd edges. Such a machine also includes means for applying adhesive to the edges of the several sheets for securing them in tubular form and employs a knife mecha- See nism for cutting the tube so formed into lengths suitable for individual bags.

In Fig. 1 of the drawings, a plurality of supply rolls are indicated at 10 and webs of paper shown at 1 to 5 inclusive are trained over guide rollers 11 to direct them toward a tuber of the kind referred to. The webs 1 to 5 inclusive form the several plies of the multiply tube from which the bags are cut and assume an offset relation to each other as illustrated in Fig. 2. This enables efficient application of adhesive and produces a desired staggering of the seams in the several tubes.

According to the present invention, a continuous web of valve material is introduced into the tube during its formation by the provision of an auxiliary supply roll 12 from which a valve web 13 is guided over a roller 14 for introduction between two of the bag plies as they enter the tuber. In the present case, the valve web 13 is shown as being introduced between the fourth and fifth plies but its introduction between any other two plies may be effected by obvious means. This web 1'3 which is usually of thin paper-like material is introduced in a position somewhat as illustrated in Fig. 2 so that upon the formation of the tube, it will register with one of the gussets that are formed at both edges of the bag. Consequently as the bag is finished and cut off, it assumes the shape illustrated in Fig. 3 and the web 13 which has been folded into the gusset occupies the position indicated at 13 in dotted lines in Fig. 3. The relationship of the valve web with the gusset of the bag is shown in Fig. 4 wherein the several plies of the bag are schematically illustrated by single lines and a heavy line indicates the position of the valve web 13.

As shown in Figs. 3 and 5, the end of the bag from which the valve is to be formed is cut with an offset to provide a projection 15 to facilitate the formation of the valve corner. After the bag has been formed and cut, the valve web 13 is pulled from its original position to a position where it projects a short distance as illustrated in Fig. 5 so that its end corresponds in position and projected length to a conventional valve part which has been inserted between the plies of the bag after the bag has been formed and cut.

One of the advantages of the present construction is that because of the length of the valve members 13in the present invention, it is securely held in the gusset folds of the bag without the necessity of adhesive or other securing means. The operation of withdrawing the valve element to the position shown in Fig. 5 is also simpler and more positive than the previously employed method of inserting a short valve part by hand.

In the completion of the bag by the method of the present invention, the extended valve corner of the bag 15 is folded inwardly to the position illustrated in Fig. 6 wherein the gusset is shown at 16. The open end of the bag is closed as by a line of stitching 17 or other means and this stitching is usually passed through a folded reenforcing strip indicated at 18. In .the process of turning in the valve corner of the bag, the projecting end of the valve member 13 assumes the conventional position illustrated in Fig. 6.

During the folding and filling of the bag, the projecting end of .the valve element sometimes becomes wrinkled so that it does not close readily after the bag has been filled and to avoid this, it has been customary in some 3 intervals while it is being incorporated in the tube from which the bags are formed.

1 claim:

1. The method of forming a multiply valve bag wherein several webs of bag stock are passed through a tuber simultaneously which comprises introducing a web of valve stock between two webs of the bag stock and feeding it through the tuber therewith, then cutting the tube so formed with the valve stock included into bag lengths, and then withdrawing the valve stock from one end of the cut length a distance suflicient to provide a valve member upon completion of the bag.

2. The method for forming a gusseted tubular multiply valve bag wherein several webs of bag stock are fed simultaneously through a machine to form them into a gusseted tube and cut the tube into bag lengths which comprises, introducing a web of valve stock between two webs of thebag stock in a position to include it in one .4 gusset of the tube, feeding said valve stock through the machine with the bag stock, and then withdrawing the valve stock from one end of the cut length a distance sufiicient to provide a valve member upon completion of the bag.

References Cited in the file of this patent UNITED STATES PATENTS 1,476,560 Witmer Dec. 4, 1923 2,260,064 Stokes Oct. 21, 1941 2,331,966 Eisgrau Oct. 19, 1943 2,432,968 Lahey Dec. 16, 1947 2,528,419 Burroughs Oct. 31, 1950 2,542,170 Weeks Feb. 20, 1951 2,651,451 Bennett Sept. 8, 1953 2,668,003 Jones Feb. 2, 1954 2,714,983 Potdevin Aug. 9, 1955 

